SHANGHAI, Mar 13 (SMM) - The aluminium ingot social inventories across China’s eight major markets stood at 1.246 million mt as of March 13, down 21,000 mt from a week ago and 23,000 mt from early March, but up 124,000 mt from the same period last year. The seasonal inventory accumulation cycle was basically over. As aluminium prices fell last week and downstream operating rates began to gradually resume in March, aluminium ingot withdrawals from social warehouses increased by 14,300 mt on a weekly basis to 156,600 last week, basically returning to the same period of previous years. Aluminium billet social inventory added 4,400 mt WoW to 167,800 mt as of March 13. Aluminium ingot withdrawals from social warehouses decreased by 2,600 mt on a weekly basis to 53,000 last week. Firm conversion margins suppressed downstream purchases. Some downstream enterprises purchased ingots and then cast them into billets.